Panama Canal: The Big Dig of Central America
By: Mary Reed first published in 2006 in Construction Equipment Guide
It cost the U.S. $375 million, thousands of lives, a movement for national independence — and a Nicaraguan postage stamp — to take over and finish construction of the Panama Canal, rightly chosen in 1996 by the American Society of Civil Engineers (ASCE) as one of the engineering wonders of the world.
And now, Panama is gearing up for the largest modernization plan in its 92-year history. Voters in October approved a $5.25 billion expansion of the canal that will include a third set of locks on the Atlantic and Pacific sides to handle the world’s largest ships.
Construction will begin in 2007 and is expected to last eight years.
A canal was first conceived in the early 16th century by King Charles V of Spain, who ordered the governor of the region of Panama to survey a route following the Chagres River to the Pacific. This was the first survey for a proposed ship canal through Panama, and more or less followed the course of the present Panama Canal.
The desire to build such a canal gained additional impetus during the 1848 Gold Rush, when prospectors could either sail around Cape Horn, cross the Great Plains, or journey across the isthmus by foot or canoe and then take ship north from the Pacific coast. The first interoceanic railroad in the world was constructed on the isthmus in 1855 but the opening of a canal would mean travelers sailing from, as an example, San Francisco to New York went from a journey of 14,000 mi. (22,500 km) around Cape Horn at the bottom of the continent to one of a mere 6,000 mi.
The United States had long been interested in the possibility of building a canal and in the latter half of the 1890s set up two Canal Commissions to look into the question of the best route. Both recommended running the canal through Nicaragua.
The French, however, had already begun the endeavor and were continuing with the task of constructing a canal located in Panama. The Compagnie Universelle du Canal Interoceanique had been granted a concession to do so in 1878 and had been at work on it since 1881. Headed by Count Ferdinand de Lesseps, world famous for building the Suez Canal, the company planned a sea-level canal, which it estimated would take 12 years to build at a cost of approximately $l30 million.
Tens of thousands flocked to invest in the project, but in late 1889 the company was declared bankrupt, defeated by months of tropical weather whose torrential rain caused constant mud and rock slides, disease-carrying mosquitoes, deadly snakes, inadequate equipment and management, and a work site situated in dense jungle spread out over mountainous terrain.
Undaunted by this spectacular although understandable failure, another French company — Company Nouvelle du Canal de Panama — was started up in l894 and took over the job. However, it too was unable to complete the canal and its assets, rights, and equipment were therefore offered for sale.
A Volcano Sways Voting
Although both Canal Commissions had recommended Nicaragua as the best place to build a canal, the engineers consulted were in favor of Panama, David McCullough wrote in “The Path Between The Seas: The Creation of the Panama Canal 1870-1914.”
There were a number of reasons to choose Panama. Among them were the canal would be shorter by more than 100 mi. (161 km), the proposed Panamanian route already possessed a railroad, and overall running costs would be lower.
Efforts to convince American legislators that Panama was a better choice were aided by two investors in the French company, Philippe Bunau-Varilla and William Cromwell. They mounted an effort to swing the vote to Panama, which would benefit them and other stockholders if the bankrupt company in which they held shares was sold to the United States. To this end they lectured, issued pamphlets, and purchased numerous advertisements in various publications, all pointing out the benefits of building the canal in Panama as opposed to Nicaragua — and in particular stressing the suggested canal site in the latter was only 20 mi. (32 km) from an active volcano.
The question was debated during the 1902 legislative session. When the matter came up for voting in the Senate, Bunau-Varilla and Cromwell carried out a masterly piece of persuasion by sending every senator a Nicaraguan stamp featuring the volcano in full eruption.
The legislature chose Panama as the site of the proposed canal, although the vote was very close, and President Theodore Roosevelt signed the Panama Canal Act into law on June 28, 1902.
The Act authorized Roosevelt to acquire not only all rights and property of every kind, “real, personal, and mixed,” and all other assets possessed by the French company, but also the necessary strip of land from Colombia, there to exercise “the right to use and dispose of the waters thereon, and to excavate, construct, and to perpetually maintain, operate, and protect thereon a canal.”
There is no doubt Roosevelt viewed the canal as being of prime importance, having declared in his December 1901 State of the Union address that “No single great material work which remains to be undertaken on this continent is of such consequence to the American people as the building of a canal across the Isthmus connecting North and South America.”
It appears his views were heavily influenced by a book written by Alfred Thayer Mahan, U.S. naval officer and scholar. This book, “The Influence of Sea Power Upon History,” was published in 1890 and advanced the theory that national and commercial supremacy were directly related to control of the sea. This point of view was important in the drive for construction of the Panama Canal.
Panama Gains Independence
Even so, the project was not set for plain sailing since before construction could begin, the United States had to negotiate a treaty with Colombia, which then controlled Panama. Despite a very generous offer — $l0 million to be paid immediately, followed by $250,000 each year of a century-long lease for 6 mi. (10 km) of land on each side of the canal — the Colombian government turned it down. It was a time for bold action.
Panama rose up and demanded its independence. The USS Nashville arrived with an official mission to protect American citizens, thwarting any attempt by Colombia to send troops to Panama by sea. The jungle prevented them from bringing military forces over a land route, so they were unable to crush the Panamanian movement.
Thus it was the Republic of Panama came into being on Nov. 3, 1903. The U.S. government obtained a treaty later that year, under which the United States gained the right to build a canal under essentially the same terms as had been offered to Colombia.
The United States began to move forward in 1904. As laid down in the Act, it purchased Compagnie Nouvelle du Canal de Panama’s assets for $40 million, taking over the project on May 4, 1904. An Isthmian Canal Commission was set up to govern the Canal Zone, although overall supervision of construction was in the hands of the U.S. Secretary of War. Expectations about the canal were plainly stated by Roosevelt:
“What this nation will insist upon is that results be achieved.”
The man who arrived in June 1904 to take up the post of chief engineer was a civilian, John Findley Wallace.
A State of Chaos
Wallace discovered the project in a state of chaos. While the French had constructed housing and other facilities for the benefit of their workforce, many of these buildings were now inhabitable. Their huge fleet of abandoned equipment — much of which was in various stages of decay — had to be examined, repaired or rehabilitated if possible, and then card-indexed for swift location as needed.
While most of the professional workers were American, laborers were largely recruited from various Caribbean countries, including Barbados, Guadeloupe and Martinique. Dozens of nations were represented by the workforce, and interpreters were in demand. Beyond skills more directly concerned with construction of the canal, many other professions were represented, ranging from secretaries, accountants to shop clerks and pharmacists, doctors and nurses.
William R. Scott spent five months in Panama, three as an employee of the Isthmian Canal Commission. In l913 he published “The Americans in Panama,” in which he mentions workers’ wages and salaries. Hourly remuneration ranged from l0 to 25 cents an hour for apprentices to 65 cents for bricklayers and up to the same amount for carpenters, coppermiths, pipefitters and linesmen. Ironworkers and machinists were paid as much as 70 cents an hour. A steam shovel operator earned between $2l0 and $240 a month. While these rates appear small, they were far more than would be paid for comparable work in the United States, and were in addition to free housing and medical care at no cost.
Wiping Out Disease
One of the first major jobs the Americans undertook was carrying out sanitary improvements to deal with the high death toll from disease, most often malaria and yellow fever. At the time, the discovery both illnesses were carried by mosquitoes was only beginning to be accepted. The effort was led by Chief Sanitary Officer William C. Gorgas of the U.S. Army. Even so, it was an uphill battle which ultimately involved adding screens to doors and windows, fumigating dwellings, and laying oil weekly on cesspools and cisterns to kill insect larvae.
In addition, the United States paved streets and constructed water and sewage systems for Panama City and Colon. Once this was done, the hitherto common use of barrels to store water for domestic use was ended, thus removing thousands of potential mosquito breeding grounds.
Rufus E. Forde contributed recollections of working on the canal to the Isthmian Historical Society in l963. Forde recalled that from a gang composed of approximately l25 workers, 40 or so would come down with malaria before noon. It was a sight so frightening, he said, that “sometimes you don’t come back after dinner.”
Canal workers were instructed to drink quinine to treat malaria, but its taste was so vile many claimed they had taken theirs when they had not in fact done so, he added.
Wallace had not supported Gorgas’ efforts because he did not believe the diseases were transmitted by mosquito, and while John F. Stevens, the chief engineer who replaced him, admitted to not being entirely convinced as to the efficacy of Gorgas’ proposed eradication program, he nonetheless supported it. Ira E. Bennett’s “History of the Panama Canal” quoted Stevens’ opinion there were three diseases on the isthmus:
“Yellow fever, malaria, and cold feet.”
Gorgas’ draconian measures succeeded and it was announced in December 1905 that yellow fever had finally been eradicated from the isthmus. However, malaria still caused many deaths among workers because surviving it did not make the patient immune to further attacks. Hospital records show that 5,609 people died from disease or accidents during the American construction era, and 4,500 of them were black employees.
Once under control, stern measures were taken to keep the isthmus disease-free. Quarantines were rigidly enforced and inoculations mandatory. Scott’s book mentions an incident in 1905 when a number of workers from Martinique initially refused to leave their ship because they believed vaccination scars were intended to mark them so they could not go home. He related that they were removed from their vessel at bayonet point and then inoculated.
Facilities for the Workforce
Chief Engineer Wallace found the going difficult. Despite all efforts, housing and food for the workers were not of acceptable quality. He expressed anger about “red tape” constantly interfering with the running of the project, and also was worried about his family being stricken with disease, particularly after his secretary’s wife died of yellow fever. There had been personality clashes with the chairman of the commission and although the commission was dissolved and a new one set up, Wallace, who had received an offer of a better paid job in the United States, resigned a year after his arrival.
Another civilian, John F. Stevens, took over as chief engineer in July 1905. He had excellent references, having been in charge of the construction of the Great Northern Railroad in the Pacific Northwest.
After Stevens’ arrival, the United States used 12,000 of its workforce to construct buildings as well as carry out excavation work. Between 1905 and 1907 clinics and hospitals, laundries, libraries, mess halls, churches, hotels, social and fraternal clubs, and many other amenities were built. Numerous workers had brought their wives and families with them, and schools were provided. Fire departments, courts and post offices came into being and shops sold household goods, canned items and perishables kept in refrigerated storage.
Saturday night dances were held at hotels and firework displays, lectures, and other types of entertainment (including a circus on at least one occasion) also were available to the workforce.
The Panama Record, published weekly, provided news of sporting events and contests, social gatherings, and notices of various sorts, as well as committee reports and official announcements.
Recreational facilities eventually included bowling alleys, gyms, ice cream parlors, billiard rooms, tennis courts and baseball parks. Contests involving various sports were held, with keen competition between teams.
The immense logistical problems involved in providing life’s necessities can be demonstrated by noting meals for the workforce required the annual baking of more than 60,000 rolls and 6 million loaves, as well as approximately 110,000 lbs. of cake.
Improving a Vital Rail Link
Another task to be accomplished was improving transportation. The Panama Railroad ran past the excavations but had descended into a degraded state. Its efficient operation was vital to the job, since there were no highways and the railroad had to move everything needed from construction equipment and building materials to food, medical supplies, and excavated material, not to mention the workforce itself.
The French company’s holdings included a number of locomotives and wagons. Most were considered too lightweight for the tasks they had to accomplish, although some were eventually rehabilitated. The rail system was overhauled and more robust American rolling stock suitable for handling the movement of heavy equipment and to haul excavated material away from the diggings were shipped in. The workforce included experienced American rail staff whose task was run the railroad — once it had been built from components shipped to Panama in a dismantled state.
Make the Dirt Fly
Roosevelt had made it plain workers were expected to “make the dirt fly,” but construction plans had to be flexible in order to meet challenges as work continued. For example, the width of the Culebra Cut was changed from 200 to 300 ft. (61 to 91 m) while after a request from the U.S. Navy lock chambers were increased to 110 ft. (34 m) wide. This was to ensure the canal would allow passage of vessels, which at the time were still themselves in the design stages.
Landslides continued to be a continual and often fatal occurrence. Exacerbated by the tropical rainy season, they also destroyed equipment and buildings and filled in newly excavated portions of the canal, which then had to be redug.
Accidents, of course, were unavoidable. A number of people who had worked on the canal reminisced about that aspect of the job at a gathering organized by the Isthmian Historical Society in 1958.
Reed E. Hopkins, former railroad conductor, recalled standing orders that if anyone was hurt, conductors had to take them immediately to the hospital. It happened daily, since although dynamite blasts were usually timed for 11:30 a.m. and 5:30 p.m., they were sometimes set off without warning and flying debris took its toll.
Gertrude B. Hoffman, a teacher, spoke about a premature blast at Bas Obispo, where the father of one of her pupils took cover in the dipper of a steam shovel. The shovel ended up entirely covered with chunks of rocks.
Charles F. Williams described seeing a train in Colon Station, its luggage car marked funeral car and behind it a coach for passengers being taken to hospital. Such cars were, he said, “regular equipment on the Panama Railroad.”
Third Chief Engineer Arrives
Chief Engineer Stevens was instrumental in persuading President Roosevelt and Congress that the canal should be built with locks, rather than the proposed sea level waterway. In strongly-worded evidence to the House Committee on Interstate and Foreign Commerce, he declared the greatest problem in the construction of any canal across the isthmus was going to be controlling the Chagres River — and equally emphatic that a system of locks would solve it. In June l906 the final vote was taken, and a lock canal was approved, albeit by a narrow margin.
However, Stevens resigned in 1907, citing personal reasons. A third commission was set up to oversee the project. It was composed mainly of military men and George Washington Goethals, then holding the rank of major in the U.S. Army Corps of Engineers, became chief engineer of the project. Being in an officer in the army, unlike the two previous chief engineers he could not leave the project until permitted to go elsewhere.
Goethals was not one to mince words. Bennett’s book relates he addressed his workforce in the stirring fashion of an army man.
“I am commanding the Army of Panama; the enemy is Culebra Cut and the locks and the dams.”
Nor did he exaggerate. The Culebra Cut is approximately 9 mi. (14.5 km) long and had to be dug through the Continental Divide. When the Americans took over, the two French companies had already excavated more than 78 million cu. yds. (60 million cu m) of which approximately 18,600 cu. yds. (14,220 cu m) of material had been taken from the Cut.
Ralph E. Avery described the French excavators in his 1913 work “America’s Triumph” in Panama. They were the type fitted with chains on buckets, which dropped spoil into hoppers which then transferred it into dump cars. It was to be over a year before steam shovels completely replaced these excavators.
Dynamite and Steampower
By today’s standards, the construction of the canal was carried out by primitive methods, since it was largely accomplished by laborers, dynamite and steam power.
Preparation for rock blasting was carried out by drills run on compressed air piped from three plants some five miles away from the work site. Operating in sets of up to a dozen, set between 6 and 16 ft. (2 and 5 m) apart, the drills cut down as deep as 27 ft. (8 m).
Steel hand drills also were used. Bennett related that holes were originally fired with the use of batteries and later by electrical current. He mentioned the largest single blast involved setting off a number of holes which together contained 52,000 lbs. (23,587 kg) of dynamite.
Goethals described the extensive use of explosives in a talk given to the National Geographic Society in 1911. Apart from blasting, dynamite also was used to break up rocks too large for the steam shovels to handle. Goethals related that in those cases three or on occasion more sticks of dynamite were laid on the rock, covered in mud, and set off by use of a slow match. Most of the dynamite was used at the Culebra Cut.
Disposal of the massive amounts of spoil involved was handled by trains pulling a score or so of Lidgerwood flat cars, each capable of hauling approximately l9 cu. yds. (15 cu m) of material. These cars were one-sided and steel plates joined each car into what amounted to a continual surface, necessary for the method used to unload them.
This was accomplished by means of attaching a car carrying a plow and another featuring an unloader at opposite ends of the train. Unloaders had a steam-driven windlass around which a wrist-thick steel cable was wound. Thus equipped, the train was driven under a frame to which the cable was attached and as the train moved on, the cable paid out until it reached, and could be attached to, the plow. Rewinding the cable pulled the plow forward, pushing excavated material off the cars to the waiting spreaders. The plow and unloader were detached and the empty train returned to the diggings. This work also was handled with Western dump cars, which ran on compressed air, and some unloading was done by hand.
As much of this excavated material as possible was recycled for such purposes as constructing a 3-mi. (5 km) long breakwater constructed as an anti-silting measure as well as building the Gatun Dam, which tamed the Chagres River and created Gatun Lake. It also was used to reclaim 500 acres (202 ha) of the Pacific. In addition, millions of cubic yards of material was dumped into the jungle.
The disposed material often included a large amount of rock and earth from landslides. In his lecture to the National Geographic Society, Goethals stated in fiscal year 1908 alone approximately 6 percent of the material removed was deposited by slides, while two years later the proportion had risen to 18 percent.
The problem was finally resolved by grading the slopes of the Cut to a less steep angle than had hitherto been attempted.
Record Amounts of Excavation
Goethals’ arrival heralded the onset of a period of record accomplishment. Bennett stated that despite the fact it was the rainy season, in August 1907 a record 1 million cu. yds. (764,555 cu m) was excavated, a figure doubled and then tripled during the following months. The workforce kept up the pace and in two years had removed approximately 73 million cu. yds. (55.8 million cu m).
In 1907 the equipment fleet increased to include 100 steam shovels, 560 drills, more than 50 cranes and 20 dredges. The annual consumption of fuel was approximately 500,000 barrels of oil and 350,000 tons (317,515 t) of coal.
Numerous American companies sent their equipment to Panama.
Among them, the Bucyrus Company of South Milwaukee, Wis., manufactured the majority of the steam shovels used on the job. Shovels also were supplied by the Marion Steam Shovel Company of Marion, Ohio, and the Harry A. Lord Company of Allegheny, Pa.
The largest shovels were 95 ton (86 t) models with 5-cu.-yd. (4 cu m) dippers, and 45- and 70-ton (41 t and 64 t) shovels also were used. In May 1912 a Marion model 9l steam shovel set a world record by moving more than 5,550 cu. yds. (4,243 cu m) of material.
One or two of the steam shovels, which worked on the canal have been traced. A Marion model 60 present in Panama in l904 was reported fronting a museum at the University of Costa Rica. Another canal-era Bucyrus steam shovel was borrowed from a private owner in Montana and exhibited in “Let The Dirt Fly,” the 1999 Smithsonian Institution exhibition devoted to the construction of the canal.
Harry A. Franck worked on the project for several months in 1912, first as a census enumerator and subsequently as a policeman. “Zone Policeman 88: A Close Range Study of the Panama Canal and its Workers,” his lively memoir of the time he spent in the Panama Zone, was one of the best selling books of 1913. He provided a colorful picture of the work carried out by the steam shovels, describing their mammoth strength coupled with the ability to work at delicate tasks such as picking up a single railroad spike.
“They ate away the rocky hills,” he wrote, “and cast them in great giant handfuls on the train of one-sided flat-cars that moved forward bit by bit at the flourish of the conductor’s yellow flag.”
Steam shovel crews consisted of a craneman who perched on its arm and the engineer who operated the controls, each shovel being accompanied by a gang of laborers. The latter came from many nations and sometimes unexpected professions. Franck noted a Spanish laborer killed at the Culebra Cut by a dynamite explosion was discovered to be a celebrated lawyer in his home country.
Steam Shovel Work Honored
The sterling work of the steam shovels is recalled in a bronze plaque commemorating Lieut. Col. David DuBose Gaillard, who oversaw excavation at the Culebra Cut between the summers of 1908 and 1913, and after whom the Cut was subsequently renamed. The plaque shows two laborers digging in the Cut, a pair of steam shovels in the background. It is now displayed at the bottom of the steps in front of the Canal Administration building in Balboa, close to the Goethals Memorial.
In addition, a stamp issued in 1951 depicted laborers from the West Indies working on the Culebra Cut, with a steam shovel shown on the far left. Steam shovels and other equipment also can be seen in murals decorating the rotunda of the Canal Administration’s building, which record work at the Cut, the Gatun Dam, and the locks.
Steam shovels working on the canal were mounted on cars running on rail lines, which were relocated as necessary by track shifters invented by William G. Bierd, who previously held the post of general manager of the Panama Railroad. With their aid, whole sections of tracks could be quickly moved between approximately 2.5 and 9 ft. (.7 and 3 m) in one “throw” when the task in hand required it.
Dredges and Hoists
Dredges working on the project included a 20-in. (51 cm) hydraulic pipe line model, manufactured by the Ellicott Machine Company of Baltimore, Md. It cost $158,000 and could excavate 750 cu. yds. (573 cu m) of material an hour.
Other dredging equipment was supplied by the Haywood Company and Froment & Company, both based in New York City, as well as the Atlantic Gulf & Pacific Company, also of New York.
A. L. Ide & Son, based in Springfield, Ill., supplied dredge engines, while centrifugal pumps were provided by the Morris Machine Works of Baldwinsville, N.Y.
The equipment fleet also included four rebuilt iron-hulled ladder dredges salvaged from the holdings of the French company. The buckets of these dredges could move 15 cu. ft. (.4 cu m) of material, working down to a 45 ft. (14 m) depth.
Equipment provided by the Brown Hoisting Machinery Company of Cleveland, Ohio, handled heavier work, such as unloading coal. Coaling cranes manufactured by Orton & Steinbrenner of Chicago, Ill., also worked on the job, and another Cleveland manufacturer with a similar name, the Browning Engineering Company, provided cranes.
Scott reported the cost of the canal up to July 1912 was $260 million, including the $40 million used to purchase the French company. By then construction and engineering had cost $152 million and sanitary improvements $15 million. Bennett set the cost of excavating the Calubra Cut alone at between $l0 million and $l5 million a mile.
Building the Locks
The construction of the canal’s giant locks provided another snapshot of just one part of the huge task facing the builders.
Some notion of the vast size of these locks is indicated by the numbers: the walls bisecting the locks into two chambers are themselves 60 ft. (18 m) wide. The thickness of side walls ranges between 45 to 50 ft. (12 and 15 m) on the lock floor, and the culverts, which carry water to the locks have a diameter of 18 ft. (5.5 m).
During the construction of the Gatun Locks, concrete was delivered by a new method involving a circular electric railroad.
Steel cars divided into two compartments (one for premeasured amounts of sand and stone and the other for cement) were loaded and sent to eight concrete mixers, each with a 64 cu. ft. (1.8 cu m) capacity. Once mixed, concrete was loaded into rail cars and rerouted to 85 ft. (26 m) high Lidgerwood cableways spanning the locks. Full buckets were caught up and carried across the lock for placement as necessary, while the empty buckets for which they were exchanged were already returning to be refilled with material for the concrete mixers so the cycle could begin again.
At Pedro Miguel and Miraflores on the Pacific end of the canal a similar system for mixing and placing concrete was operated with the aid of cranes and steam locomotives Lt. Col. Harry F. Hodges was in charge of the design and erection of the lock gates. McClintic-Marshall Construction Company, of Pittsburgh, Pa., was awarded the contract for this part of the job. Ranging in height from 47 to 82 ft. (14 to 25 m), the gates are 7 ft. (2 m) thick, and comprise two leaves over 60 ft. (18 m) wide, weighing between 390 and 730 tons (354 and 662 t) apiece.
Franck’s book provides a glimpse of the construction of the Gatun Locks. Describing its steel gates, which he saw standing ajar, as akin to “an opening in the Great Wall of China.” He goes on to say, “On them resounded the roar of the compressed-air riveters and all the way up the sheer faces, growing smaller and smaller as they neared the sky, were McClintic-Marshall men driving into place red-hot rivets,” tossed up to them from workers at the forges, their trajectory “glaring like comets’ tails against the twilight void.”
Ships are not permitted to pass through the locks under their own power. General Electric in Schenectady, N.Y., provided “mules,” as the electric locomotives, which pull vessels through the locks are known.
A Greater Work Than They Realized
The importance of the canal was highlighted in November 1906 when Theodore Roosevelt visited Panama to inspect progress on the job, the first time a sitting president had left the country.
In a speech to the workforce at Colon, after complimenting the “steam-shovel man” as “the American who is setting the mark for the rest of you to live up to.” Roosevelt went on, “This is one of the great works of the world; it is a greater work than you, yourselves, at the moment realize.”
In his speech, Roosevelt promised to see if he could arrange for “some little memorial, some mark, some badge, which will always distinguish the man who did his work well on the Isthmus,” and indeed this came to pass. Medals struck from scrap metal taken from abandoned French equipment were issued to Americans who had worked for two years on either construction or the railroad. Bars marking each subsequent two year period of service on the project were issued thereafter.
The distribution of 50,000 bronze Panama Canal Completion Medals marked the opening of the s-shaped 51-mi. (82 km) long waterway on Aug. 15 1914.
When the United States took over building the canal — and for some time afterwards — naysayers said such a waterway could never be built. Yet in only 10 years persistence, grit, and technical knowledge, aided by an army of laborers and heavy equipment, saw the job through to completion.